The invention relates to an air spring for preventing the shakes of a machine component mounted on the area subject to the generation of vibrations, and particularly, to an air spring structure for isolating a suspended rotator by absorbing/preventing the vibrations of the rotator generated in a commercial or household machine. Specifically, the air spring helps to prevent fouling of the rotator in which the rotator strikes surrounding structures. The fouling is caused by the rotator spinning while unbalanced, thereby generating irregularly complex forces, each of the complex forces having dynamic displacements or amplitudes, different from one another, due to the unbalanced mass and center of a suspended rotator.
Generally, coil springs have been used in preventing vibrations in machines. A conventional coil spring can stop an up and down trembling motion, also called general dynamic displacement. But, in the case of a rotator suspended by a hooking member with unbalanced center or gravity by a specific dynamic displacement moving to and fro, left and rightward, and up and downward, the oscillating amplitudes of the rotator are increased differently at any direction, while the complex force directions were made irregular, thereby creating specific excessive shakes. A fouling phenomena occurs as a result of the rotator contacting surrounding structures which leads to failure or the breakage of machine components.
The typical example of a suspended rotator is a rotating barrel in a washing machine, in which the rotating barrel is mounted in an external barrel using a coil spring as shown in FIG. 12. For example, external barrel 2 is provided with rotating barrel 3 supported rotatably on rotating shaft 4, which is passed through the bottom center portion of external barrel 2. Rotating shaft 4 is connected through pulley 9 to motor 8 mounted on the bottom of external barrel 2. Bracket 5 projects from the lower periphery of the external barrel 2. Hooking member 6 fixed on the upper portion of cabinet 1 is passed through bracket 5 to couple at its lower end the coil spring 7. Thus, when rotating barrel 3 is rotated by pulley 9 during the operation of motor 8, coil spring 7 absorbs the vibrations of external barrel 2.
But, rotating barrel 3 of the suspended rotator in a washing machine has a center of rotation different from its center of gravity because of the random state of the washing materials. The unbalanced state of rotating barrel 3 induces different amplitudes or irregular complex forces in each direction, called specific excessive shakes. This causes the fouling by hitting of surrounding structures, for example cabinet 1, around the external barrel 2. Thus, in order to prevent the fouling phenomena, the absorption/prevention of specific excessive shakes in each direction as well as heneral vibrations is required.
The coil spring structure can only absorb general vibrations moving upward and downward, for example vertical dynamic displacements, but it has difficulty preventing the specific excessive snakes. As the mass and weight of rotating barrel 3 is uneven, the oscillating motions of hooking member 6 having a predetermined length is made to move upward, downward, leftward and rightward or non-uniform complex forces different from one another in each direction while being relatively larger. As a result, a fouling phenomena can occur.
If coil springs each having a different stiffness are individually mounted at different positions, the center of a rotator moves in an oval pattern during the operation of a suspended rotator centering on the X-axis and the Y-axis. When forced vibrations (w) were larger than natural frequency (wny) of Y-axis direction but less than natural frequency (wnx) (wny&lt;w, wnx &gt;w), an off-balanced rotator is reversely rotated. When forced vibrations (w) were equal to natural frequency (wny, wnx), the resonant phenomena occurred to induce a more serious fouling phenomena.
In a shake preventing structure using a conventional coil spring shown in FIG. 12, the vibrations of rotating barrel 3 are transferred through the coil spring's elastic force to bracket 5 to the upper portion of coil spring 7, returning it downward through coil spring's turns to the lower end of hooking member 6 and delivering it again through hooking member 6 to the upper portion of cabinet 1. At that time, the vibration of rotating barrel 3 generate noises due to its rotation as well as secondary noises due to dynamic motions in the course of passing each turn of coil spring 7. It is undesirable in the fact that these secondary noises resonate and are amplified by structures surrounding the rotator.
The other shake preventing structure, performing better than a conventional coil spring, is shown in FIG. 13. A plurality of bodies B are provided with a rubber liner L and at least one flange Pg formed at the opening portions of its upper and lower ends. Rubber liner L having air inflated therein is coated by two layers P1 and P2 of fiber reinforced rubber materials. On the outermost to rubber liner L there is formed an outer compressed rubber sheath C. Finally, the flanges Pg are each sealed to form an air spring.
The air spring is more effective than a coil spring in absorbing the vibrations of industrial beavy machinery fixed in a predetermined position, for example a pump, a blower and a compressor, etc. Nevertheless, it does not work well in preventing the fouling phenomena, because the X-axis and Y-axis dynamic displacements of a suspended rotator are not completely removed.
This air spring generally had horizontal stiffness (kh) of about 0.2 to 0.3 relative to vertical stiffness (kv) so that upward and downward dynamic displacements are more or less absorbed. But, if the mass and weight of a rotator were uneven, the dynamic displacements, such as specific excessive shakes, are not prevented, the amplitudes of specific excessive shakes at each direction are made larger, and their complex force directions are irregular, thereby inducing the fouling phenomena by the rotator striking surrounding structures.
This air spring includes body B provided with compressed rubber inner liner L, two reinforced fiber rubber layers P1, sheath C made of compressed rubber materials and at least one of the flanges Pg sealed at its upper and lower opening portions. Therefore, manufacturing is very complicated, expensive, and mass-production is very difficult.
The main object of the invention is to provide an air spring structure free from the shakes of a suspended rotator by absorbing/preventing the vibrations of rotators mounted in commercial wr household machine equipment, in which it prevents the fouling phenomena in which the rotator strikes surrounding structures while rotating in an unbalanced condition thereby generating unevenly complex forces, each complex force having dynamic displacements or amplitudes different from one another due to the unbalanced mass and weight of a rotator.
The other object of the invention is to provide an air spring structure for reducing the noises of a suspended rotator during rotation.
Another object of the invention is to provide an air spring structure for effectively preventing the shakes of a suspended rotator or a fixed structure.
Another object of the invention is to provide an air spring structure having a simple configuration and features which can be easily manufactured by mass-production at a reduced manufacturing cost.